Explosives tester



April 27, 1954 C. J. ZABLOCKI El AL EXPLOSIVEIS TESTER 2 Sheets-Sheet 1 Filed Jan. 15, 1952 INVENTORS C. J. ZABLOCKI F. W. HAYWARD RAM April 1954 c. J. ZABLOCKI EI'AL 2,676,484

' EXPLOSIVES TESTER Filed Jan. 15, 1952 2 Sheets-Sheet 2 FIG.3.

INVENTOR5 C. J. ZABLOCKI By E w. HAYWARD RwALA/m ATTYS.

an aperture extending from the hollow portion to the end of element 28 in which is disposed wires 3| forming a part of the firing circuit. A pellet 32 of plastic or other suitable material is disposed within bore 27 and between the pressure bar l and the charge. This pellet is inserted for the purpose of preventing splintering or other distortion of the pressure bar when a charge is fired. Obviously, were a charge of small capacity to be tested, this pellet could be omitted.

Suitably secured to base 1 adjacent the explosion chamber is a plate 33 whichprovides a support for uprights 34 and 35. Rotatably mounted between these uprights is a cross bar 36 made of insulating material and providing a suspension means for pendulum 31. Adjacent the lower end of the pendulum is a weight 38 of known mass which is disposed in abutting relation to the end of pressure bar l5 in the normal position of the pendulum. This weight may be removably mounted on the pendulum in any suitable manner so that it can be replaced by a different weight in order to provide for testing explosives of a wide range of capacities. At the lower end of pendulum 31 is an electrode 39 and at the upper end thereof is a terminal 40 which is suitably wired to the electrode.

At the upper ends of uprights 34 and 35 is se-' cured a fiat cover member 4| which is additionally supported by brackets 42 and 33. On the upper surface of the cover member is mounted a U- shaped frame 44 which rotatably supports reel 45. At the outer end of the cover member is fixed a bifurcated supporting bracket 46 which is made of insulating material and which supports the upper end of an arcuately shaped metallic guide channel 41. This guide channel is provided with upwardly and inwardly extending flanges 48 which provide a guide means for recording paper 49, which may be of the wax base variety. The lower end of theguide channel is supported by a lower cross bar 5| which is also made of insulating material. Guide channel 41 is further provided with an electrical terminal 52. It is clear that guide channel 41 and pendulum 3! are insulated both from each other and from the rest of the structure by means of the insulated cross bars 36 and 51 and bracket 46.

The wax base recording paper extends from reel 45 through guide channel 41 and over the lower cross bar 51 to a winding reel 53 which is supported on base 33 by bracket 55 and is provided with an operating handle 54.

Further mounted on base I is an electrical control box 56. The details of construction of this box form no part of the present invention and it may be assembled in any well-known manner. Wires 5'! extend from this box and are-connected to wires 3! provided in the charge retaining means. On box 56 are provided several switches, one of which serves to energize the firing circuit. Leads 58 are also provided on the electrical control box, one of which is attached to terminal 52 and the other to terminal 40 on the pendulum. This circuit is also energized through the medium of a suitable switch on the control box.

In the use and operation of this explosives tester the following procedure is carried out. The charge to be fired is placed within hollow portion 29 of the retaining element 28 and with pellet 32 is fitted within collar 26 so that the pellet is in abutting relation with pressure bar I5. The sparking and firing circuits are then energized by operation of the proper switches on the control box. Upon firing a compression wave 4 travels the length of pressure bar I 5 and into the weight 38 on pendulum 31. This compression wave returns as a tension wave and, when this wave returns through the contact between the weight and pressure bar, a separation occurs causing the pendulum to swing. The energized electrode 39 sparks to the guide channel 41 providing a series of perforations in the wax base recording paper.

. of the present invention are possible in the light of the above teachings. For example, a switch could be provided in the firing circuit whereby the explosive would only fire when the sliding door 8 was in a closed position. Further within the purview of this invention is the provision of a means for retaining the pendulum at the outermost point of its swing to prevent jarring the pressure bar on the return swing of the pendulum. Such means could take the form, for example, of a ratchet wheel mounted on the upper cross bar 36 engaged by a pivoted pawl mounted on upright 34. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment of any royalties thereon or therefor.

What is claimed is:

1. An explosive tester comprising an explosion chamber, a pressure bar mounted in an end wall of said explosion chamber and extending therethrough, a pendulum, means pivotally suspending said pendulum so that the free end thereof is in contact with the externally extending end of said pressure bar in the initial position of rest whereby upon initiation of an explosion in said chamber, the explosive force is transmitted through said pressure bar by a compression wave to said pendulum which swings in response thereto, and means for recording the angular movement of said pendulum from the initial position of rest.

2. An explosive tester comprising an explosion chamber, a pressure bar resiliently mounted in an end wall of said explosion chamber and extending horizontally through said wall, a pendulum suspended so as to have the free end thereof normally in contact with that end of said pressure bar remote from said explosion chamber and adapted to swing in a plane including the longitudinal axis of the pressure bar whereby upon initiation of an explosion in said chamber the explosive force is transmitted through said pressure bar by a compression wave to said pendulum which swings in response thereto, and means for recording the angular movement of said pendulum from the initial position of rest.

3. An explosive tester comprising an explosion chamber having an aperture in an end wall thereof, a pressure bar, mounting means secured to said end wall for resiliently supporting said pressure bar within said aperture, said pressure bar extending horizontally through said mounting means from the interior of said explosion chamber, a pendulum pivotally suspended so that .the free end. thereof normally contacts the external end of said pressure bar remote from said explosion chamber, and recording means to trace the angular movement of said pendulum from the initial position of rest in response to an explosion in said chamber.

4. An explosive tester comprising an explosion chamber, a pressure bar mounted to extend through an aperture in a wall of said chamber, charge retaining means held in abutting relation to the end of said pressure bar within said explosion chamber, a pendulum, means pivotally suspending said pendulum so that the free end thereof normally contacts the externally extending end of said pressure bar which is remote from said explosion chamber, whereby upon firing a charge held within the charge retaining means the explosive force is transmitted through said pressure bar to said pendulum which swings in response thereto, and means for recording the angular movement of said pendulum.

5. An explosive tester as recited in claim 4, wherein the recording means includes a sparkemitting electrode mounted on the pendulum and an arcuately shaped member arranged adjacent the path of movement of said electrode.

6. An explosive tester comprising an explosion chamber, a pressure bar mounted in an end wall of said explosion chamber to extend horizontally therethrough, a pendulum, means pivotally suspending said pendulum, a weight mounted on the free end of the pendulum so as to normally contact the externally extending end of said pressure bar which is remote from the end in said explosion chamber, an electrode mounted on said pendulum, means for providing an electrical charge on said electrode sufficient to cause sparking therefrom, an arcuately shaped member providing a return path to said charging means and arranged to substantially conform to the path of movement of said electrode and spaced a spark ing distance therefrom, and wax base recording paper on said arcuately shaped member whereby, when said pendulum swings in response to an explosion in said explosion chamber, the charged electrode sparks to the arcuately shaped member providing a permanent record of the degree of swing of said pendulum on the wax base paper.

'7. An explosive tester comprising an explosion chamber, a pressure bar resiliently mounted through an end wall of said explosion chamber and adapted to extend horizontally therefrom, a pendulum, means pivotally suspending said pendulum, a weight mounted on the free end of the pendulum so as to normally contact the exteriorly extending end of said pressure bar remote from said explosion chamber, an electrode mounted on said pendulum, means for providing an electrical charge on said electrode sufiicient to cause sparking therefrom, an arcuately shaped member having paper guide means and providing a return path to said charging means, the arcuately shaped member being so disposed and arranged as to substantially conform to the path of movement of said electrode and spaced a sparking distance therefro a, and a pair of winding reels, one of said reels being rotatably mounted at one end of said arcuately shaped member and adapted to receive a length of wax base recording paper from the other reel through said guide means whereby a continuous recordation of successive swings of the pendulum is provided.

8. An explosive tester comprising means forming an explosion chamber, a pressure bar mounted through an end wall of said explosion chamber, means includi g a recessed member for retaining a charge held in abutting relation to the end of said pressure bar within said explosion chamber, a pendulum pivotally mounted so that the free end thereof normally contacts the exteriorly extending of said pressure bar which is remote from said. explosion chamber whereby upon initiation of an explosion in said chamber the explosive force is transmitted through said pressure bar by a compression wave to said pendulum which swings in response thereto, and means for recording the degree of angular move-- ment of said pendulum from the normal position.

9. An explosive tester comprising an explosion chamber, a pressure resiliently mounted to extend through an end wall of said explosion chamber and adapted to extend horizontally therefrom, charge retaining means mounted in abutting relation to the end of said pressure bar within said explosion chamber, a pendulum, means pivotally mounting said pendulum, a weight mounted on the free end of the pendulum, said weight normally contacting the exteriorly extending end of said pressure bar which is remote from said explosion chamber, said pendulum being adapted to swing in a vertical plane which includes the longitudinal axis of the pressure bar, an electrode mounted on said pendulum, means for providing an electrical charge on said electrode sufiicient to cause sparking therefrom, an arcuately shaped member having guide means and providing a return path to said charging means and arranged to substantailly conform to the path of movement of said electrode and spaced a sparking distance therefrom, and a pair of winding reels, one or" said reels being rotatably mounted at one end of said arcuately shaped member and adapted to receive a length of wax base recording paper from the other reel through said guide means whereby upon initiation of an explosion said explosive force is transmitted through said pressure bar by a compression wave to the pendulum which swings in response thereto and the degree of angular movement of said pendulum is recorded by the charged electrode sparking through the wax base recording paper to the arcuately shaped member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,656,246 Stevenson Jan. 17, 1928 2,518,350 McCormick Aug. 8, 1950 2,578,803 Holmberg et al. Dec. 18, 1951 2,601,778 Gordon July 1, 1952 

